LATER MORAINES OF LAKE MICHIGAN, SAGINAW, AND HURON-ERIE LOBES. 233 



into Montcalm County, where they turn southward across eastern Montcalm and northeastern 

 Ionia counties to the Grand River valley. Just north of the river the outer of these moraines 

 splits into three and the inner into two members. 



The relatively weak inner moraine passes southward from southeastern Clare County through 

 western Isabella County 2 to 5 miles from the inner edge of the stronger moraine. It crosses 

 Chippewa River at the great bend a few miles west of Mount Pleasant, assumes considerable 

 strength for a few miles, and bears southeastward into northwestern Gratiot County, its width 

 being increased from less than 2 miles to about 4 miles. It then runs southward with diminish- 

 ing strength through the western edge of Gratiot County to the Grand River outlet in the 

 northwestern corner of Clinton County. 



A small moraine, termed the Gladwin, lies east of the strong West Branch morainic system, 

 with which it is connected only at its north end in southwestern Ogemaw County. It passes 

 southwestward into northern Gladwin County, where it is interrupted for a few miles. It sets 

 in again about 5 mdes northeast of Gladwin and leads southwestward, passing just north of 

 that town across western Gladwin County. It continues across southeastern Clare to central 

 Isabella County just west of Mount Pleasant, crosses Chippewa River, and goes southeastward 

 into Gratiot County. A ridge parallel to it on its inner border leads southeastward from just 

 east of Mount Pleasant to St. Louis in Gratiot County. The two ridges unite near Ithaca and 

 run southward to the Grand River outlet. From the outer ridge a spur leads southward from 

 the northern part of Gratiot County to Elwell and may be continued a few miles farther south 

 in a ridge that runs from about 3 miles southwest of Ithaca southward to the Grand River 

 outlet. It thus appears that this moraine, which is a single ridge in the district north from 

 Mount Pleasant, is separable into two and in places into three ridges between Mount Pleasant 

 and the Grand River outlet. Beyond that outlet it finds continuation in the Flint moraine 

 discussed by Mr. Taylor (pp. 241-243). 



TOPOGRAPHY. 



ALTITUDE. 



The highest part of the West Branch morainic system is in southeastern Roscommon 

 County, where it reaches an altitude of about 1,400 feet. A considerable part of it, from 

 Harrison northeastward to Au Sable River, is above 1,200 feet, but its inner border falls to less 

 than 1,000 feet. The interlobate spur between Au Sable River and the Lake Huron shore in 

 Alcona County is largely above the 900-foot contour and in places above the 1,000-foot contour, 

 and within 2 or 3 miles of the shore of Lake Huron it has points fully 800 feet above sea level, 

 or more than 200 feet above lake level. 



From Harrison southward the West Branch morainic system shows a steady decrease in 

 each of its members clear to the Grand River outlet. The outer members are each a little 

 higher than the next inner one throughout this entire distance. The outermost member near 

 Ionia stands over 800 feet above sea level at the bluff of the Grand River outlet; the second is 

 nearly 800 feet where it comes to the bluff ; the third is but little above 700 feet at the bluff in 

 northwestern Clinton County. The outer member shows the greatest range — about 600 feet — 

 in altitude ; the inner member, or rather the inner edge of the main system, descends little more 

 than 300 feet from the border of the Au Sable Valley to the Grand River outlet. 



The Gladwin moraine stands above 900 feet for a few miles in southwestern Ogemaw 

 County and mainly between 800 and 900 feet from the Ogemaw County fine to the Chippewa 

 Valley at Mount Pleasant. A small tract in southeastern Clare County stands above 900 feet. 

 From Mount Pleasant southward the 800-foot contour is reached only for a short distance in 

 southeastern Isabella County. Elsewhere between Mount Pleasant and the Grand River outlet 

 the altitude is between 700 and 800 feet. 



RELIEF. 



The relief of the moraine above the inner border district is greatest in Ogemaw and 

 Roscommon counties, amounting in places to nearly 500 feet, and throughout much of the 

 distance from Au Sable River to southern Clare County is more than 200 feet. Southward 



